There's an interesting paragraph 0005, i believe, where it mentions that DC and ultrasonic motors have difficulty generating enough torque without high voltage and/or extra gearing.

Excellent catch. It is true that it is problematic to generate high torque with small diameter motors. That is why the ring-USM is so effective because the diameter of the motor is essentially the diameter of the lens barrel. With such a large diameter, only relatively small forces must be generated in the ring to get large values of torque.

I wonder if there are patent issues that make it difficult for Pentax to go to ring ultrasonic motors, or did they go to ultrasonic micromotors for SDM simply because it was the cheapest, fastest, and easiest way to get to a quiet focusing lens, that still was backwards compatible with screw drive?

My guess is that the biggest challenge in implementing the focus motor method outlined in the patent will be the automatic control algorithm of the lens. Magnetic fields do not collapse instantly in motors, so it might be challenging to prevent overshoots. It will need the equivalent of a highly sophisticated brushless motor controller.

I really hope they don't put it in a 400mm f4 because my wife would not be happy with me. I really loved my DA300 but it was slow if you lost track of your subject. Ring motors (I guess that's what it is)really are fast

I dunno if this patent id for 645D lenses.
What I know is 645D lenses wil offer something else (on top of?) than screwdriver AF.

Why? Because latest pics from 534D+lens show an AF/MF switch on the lens. Simple as that.

Sorry to burst your bubble but the good old FA645 75/2.8 has an MF/AF switch as well.
The most likely reason for this switch on the new generation of lenses is that they almost certainly contain the manual overiding feature, otherwise interfering with the old type MF/AF switch on the focus ring.

Sorry to burst your bubble but the good old FA645 75/2.8 has an MF/AF switch as well.
The most likely reason for this switch on the new generation of lenses is that they almost certainly contain the manual overiding feature, otherwise interfering with the old type MF/AF switch on the focus ring.

Why would they use both an AF/MF witch on the barrel and on the focussing ring at the same time? I just can't see.

Why would they use both an AF/MF witch on the barrel and on the focussing ring at the same time? I just can't see.

They don't. Theres no AF/MF switch on the 645 bodies. It's on the lenses. The focus ring slide AF/MF switch used on the 645 lenses (except the 75mm) and the FA* lenses is faded out (like on the DA lenses) and replaced with a switch. This is probably to make it compatible with AF with manual override.....

Hoya, like Schott and all glassmakers in the world, will sell glass to anyone interested. Go visit their website to see their catalog. Lens designers work with all glasses from all manufacturers when designing lenses, be it for photography or for other purposes (my job title is "optical designer" so I do know a few things).

Tokina license designs from Pentax, sometimes co-develop them. Just like Toyota shared the Matrix with Pontiac and called it Vibe. Just like Pentax licensed their cameras to Samsung. Samsung does not own Pentax because of that, or vice-versa.

And for the record, Tokina lenses do not have SMC nor weather seals. They are the same lens designs, not the same lenses.

Hoya, like Schott and all glassmakers in the world, will sell glass to anyone interested. Go visit their website to see their catalog. Lens designers work with all glasses from all manufacturers when designing lenses, be it for photography or for other purposes (my job title is "optical designer" so I do know a few things).

Tokina license designs from Pentax, sometimes co-develop them. Just like Toyota shared the Matrix with Pontiac and called it Vibe. Just like Pentax licensed their cameras to Samsung. Samsung does not own Pentax because of that, or vice-versa.

And for the record, Tokina lenses do not have SMC nor weather seals. They are the same lens designs, not the same lenses.

yeah... I get all that... and Tokina buys their glass from Hoya. What's wrong with that statement?

Tokina has very strict standards that their lens elements need to meet, and so far, only Hoya has been willing to produce glass elements to those standards. The low-end stuff can use glass from any supplier, but most of their line is built with Hoya glass.

They do, and they don't. The statement is not "wrong" but it is innacurate.

Tokina will design lenses (or Pentax will, or Canon, or anyone) by identifying the right parameters that each glass element has to have. These parameters include refractive index, density, etc, all function of wavelength.

THEN the designer (from any company) will look through catalogs in order to find types of glass that match those parameters. Usually it's not a perfect match, so the designer goes back and tweak the design, and goes back and forth.

So a lens can have a first element made of GG375 glass from Schott, a second element made of FBSD17 from Corning, and a third element made of LAC9 from Hoya. The designer does not care who made the glass, as long as it fits the optical properties that are needed to design the lens.

That's why your sentence is innacurate. Tokina designer are not bound to Hoya glass, and no designer would accept to work in those conditions. Nor is Hoya glass better or worse than Corning, Ohara, Schott, or any other manufacturer's glass. All those companies have catalogs of various glass types with various properties. That's all.

Thanks bdery for the description of how the process works. I think everyone makes assumptions as to how things work, even though most people don't have a clue about the workings of things outside their own industry.

They do, and they don't. The statement is not "wrong" but it is innacurate.

Tokina will design lenses (or Pentax will, or Canon, or anyone) by identifying the right parameters that each glass element has to have. These parameters include refractive index, density, etc, all function of wavelength.

THEN the designer (from any company) will look through catalogs in order to find types of glass that match those parameters. Usually it's not a perfect match, so the designer goes back and tweak the design, and goes back and forth.

So a lens can have a first element made of GG375 glass from Schott, a second element made of FBSD17 from Corning, and a third element made of LAC9 from Hoya. The designer does not care who made the glass, as long as it fits the optical properties that are needed to design the lens.

That's why your sentence is innacurate. Tokina designer are not bound to Hoya glass, and no designer would accept to work in those conditions. Nor is Hoya glass better or worse than Corning, Ohara, Schott, or any other manufacturer's glass. All those companies have catalogs of various glass types with various properties. That's all.

Sorry that is as much speculation as what I'm going to present...
Tokina designs very few lenses for DSLR's. Most are probably Pentax designs. Kenko also sell lenses and I don't know if they are just rebranded Tokinas (opps looks like they are just tokinas.).. Whole things a mess. They also sell K mount film cameras. And Tokina and Kenko are one in the same by direct purchase.http://www.kenko-tokina.co.jp/imaging/index.html

See:Kalle Pahajoki The Hoya – Pentax – Tokina – Tamron (and Samsung) Conundrum: Who owns who
As to the blanks this is a bit trickier. Tokina has some relationship to Hoya and Pentax that will probably involve some minor "restrictions" on where they come from. Is in totally exclusive? Probably not but in all liklihood Hoya is preferred supplier and in a sense Tokina may not be free to buy anywhere.
It is not even possible to define the Hoya/Tokina connection much less ther purchasing agreements.
As to owning Tokina, to reiterate the only "smoking gun".Pentax and Samsung Partnership Not Perfect | PhotographyBLOGPentax’s relationship with parent company Hoya was questioned, with Mr Iue replying that “Hoya is really serious about Pentax, as it’s a well-known consumer brand, which Hoya isn’t”. Mr Iue admitted that Hoya bought Pentax predominantly for their medical division and expertise, but they did also want the camera part too. Hoya firmly denied any plans to sell the Pentax photo division to Samsung or any other company, commenting that they had only just bought the company. Similarly, Hoya aren’t planning to sell the lens-maker Tokina, which they also own, or to merge it with Pentax. Hoya ownes Tokina??? : Pentax SLR Talk Forum: Digital Photography Review
Bottom line guess for me is that I doubt that Tokina can just go blank shopping without considering Hoya first......
Just for fun a Kenko p/s and slr.\

Both Korean and Japanese companies tend to work in groups with favored relationships among them. Those arrangements, preferences, and expectations may well go beyond written contracts.

A Western engineer may look for parts in a series of catalogs. An Asian engineer must be aware of these relationships.

And all of this will vary from company to company and from time to time.

As usual, the people who really understand what's going on are those who are least likely to share that knowledge.

That doesn't mean we cannot have fun speculating as long as we understand that we're only ..... speculating. If we're paid for it, we're "industry analysts". If not, we're generally just killing time with an intellectual exercise.

Yeah, somehow being an engineer, although not an optical one, makes me think you don't just make up parts hoping to find them in catalogs with just those parameters -- what if it's off my 1%? You'd rather move that element, right? Same with electronics -- resistors come in discrete resistances, etc.

See:Kalle Pahajoki The Hoya – Pentax – Tokina – Tamron (and Samsung) Conundrum: Who owns who
As to the blanks this is a bit trickier. Tokina has some relationship to Hoya and Pentax that will probably involve some minor "restrictions" on where they come from. Is in totally exclusive? Probably not but in all liklihood Hoya is preferred supplier and in a sense Tokina may not be free to buy anywhere.
It is not even possible to define the Hoya/Tokina connection much less ther purchasing agreements.
As to owning Tokina, to reiterate the only "smoking gun".Pentax and Samsung Partnership Not Perfect | PhotographyBLOGPentax’s relationship with parent company Hoya was questioned, with Mr Iue replying that “Hoya is really serious about Pentax, as it’s a well-known consumer brand, which Hoya isn’t”. Mr Iue admitted that Hoya bought Pentax predominantly for their medical division and expertise, but they did also want the camera part too. Hoya firmly denied any plans to sell the Pentax photo division to Samsung or any other company, commenting that they had only just bought the company. Similarly, Hoya aren’t planning to sell the lens-maker Tokina, which they also own, or to merge it with Pentax. Hoya ownes Tokina??? : Pentax SLR Talk Forum: Digital Photography Review
Bottom line guess for me is that I doubt that Tokina can just go blank shopping without considering Hoya first......
Just for fun a Kenko p/s and slr.
\

Jeffkroll,

The Kenko KF-1n and KF-2n SLR bodies are Nikon F Ai mount and the KF-3yc are Yachica/Contax mount and of course the KF-4PK is K-mount. However, that is an interesting market strategy.